I've now read volumes 1-3 of this manga, as translated by Viz. It's written by Yuu Watase, who is better known for Fushigi Yuugi and Ayashi no Ceres. But I like Alice 19th far better than either of those.
This isn't to say that Alice 19th is ground-breaking in any way, shape, or form. It's a pretty typical shoujo manga. The artwork is good. The translation is pretty good, too (very important). The story itself is part Card Captor Sakura, part Fushigi Yuugi, and part Sailor Moon. If you know anything about shoujo manga, you know this story: young, adolescent girl discovers magical bunny rabbit and then learns she has power of her own. Now she must stop evil and still try to live a normal life (and maybe get the guy she's been crushing on).
Manga such as these have all the hallmarks of a deep-set "moral." In the case of Alice 19th, the most basic message is: "Communicate!" The protagonist, Alice, is the shy type of girl who never speaks up for herself. But now she has to master 24 magical words. As she does so, not only will she be able to fight the darkness within people (which amounts to various forms of negativity, such as "hatred" and "rejection"), but she also finds her voice.
Still, everything in moderation: Alice learns that words can hurt as well as heal. In a hot-headed moment, she tells her sister Mayura that she wishes Mayura would disappear. And--because Alice's words have power--Mayura does just that. Leaving Alice to regret her words, even as she struggles to find her sister.
Things get darker for Alice when Mayura returns, but she's been turned into a conniving bitch.
Like most shoujo manga, Alice 19th turns the everyday troubles of adolescents into something fantastic. But deep down it's all the usual troubles: how different and more complicated things become as you get older. Your sister was your best friend and now she's your worst enemy. You used to talk to your parents all the time and now you feel like you can't. You like that guy, but you just can't bring yourself to tell him.
You know, Stephen Dobyns has a great poem (well, he has many) in his collection Cemetery Nights called "Missed Chances." It holds the same themes in it as Alice 19th: the regret of things said and unsaid. A simple enough lesson, but in both cases (in "Missed Chances" and in Alice 19th) it's packaged as something far more engaging and palatable. I recommend reading both.